our tax code and something that provides both an incentive for companies to set up entities (if only a po box) in other countries and an avenue for foreign companies to avoid paying US taxes.
As an example, let's say I'm Samsung. My offices here in the US can "buy" TV's from Samsung Japan. I can "buy" the product for a high price and sell it here at break even. That allows me to "send" my US profits back to Japan, where I'll pay less taxes. This is where we have issues with trade deals and the like.
And, don't kid yourself, one group very worried about trump are accounting firms. The harder the tax code can be crafted, the more business there is for them.